Making oligomers by catalytic chain transfer (CCT) is inexpensive and technologically convenient. One problem with CCT, however, is removal of the CCT catalyst from the final product. Since current CCT catalysts are based on cobalt chelates, the CCT catalysts are inherently colored. This color cannot be tolerated by some oligomers such as those designed for use in clearcoats.
One solution is to pass the reaction mixture through sorbents (see U.S. Pat. Nos. 5,726,263 and 5,750,772). This approach, however, requires addition of at least 50% more additional solvent. This solvent must be removed later. Thus, the dilution adds additional cost to the process.
There remains a need for making colorless oligomers through CCT in a convenient and inexpensive way.